Harmful Effects of Pesticides on Non-target Organisms

Md. Wasim Aktar2. US EPA. 2000. Reregistration eligibility science
Pesticide Residue Laboratory, Department ofchapter forchlorpyrifos. Fate and environmental
Agricultural Chemicals, Bidhan Chandra Krishirisk assessment chapter(Revised June).
Viswavidyalaya, Mohanpur-741252, Nadia, Westchlorpyrifos/efedrra1.pdf.
Bengal, India3. Cox, C. 2000. Lethal lawns: diazinon use
Introduction Pesticides are found as commonthreatens salmonsurvival. Journal of Pesticide
contaminants in soil, air, and water, and onReform 20(2). 2-7.72. U.S. EPA. Office of
non-target vegetation in our urban landscapes.Prevention, Pesticides, and Toxic Substances.
Once there, they can harm plants and animals1996. Reregistration eligibility decision
ranging from beneficial soil microorganisms and(RED):trifluralin. Washington, D.C., April.
insects, non-target plants, fish, birds, and other4. Koyama, J. 1996. Vertebral deformity
wildlife. Table 1 summarizes the harmful effects tosusceptibilities ofmarine fishes exposed to
non-target organisms of some commonly usedherbicide. Bull. Environ. Contam. Toxicol. 56:655-662.
urban herbicides.5. Extoxnet. 1996. Pesticide Information Profile:
Table 1 . Harmful effects of selected herbicides onoryzalin. June.
non-target organisms Source: Sanders, 19696. Shafiei, T.M., and H.H. Costa. 1990. The
Fish When pesticides contaminate water they cansusceptibility andresistance of fry and fingerlings
be harmful to the fish that live there. Insecticidesof Oreochromis mossambicus Peters to some
can be particularly toxic to fish. Chlorpyrifos, apesticides commonly used in Sri Lanka. Journal
common contaminant of urban streams,18 is veryAppl. Ichthyol . 6:73-80.
highly toxic to fish, and has caused fishkills in7. Folmar, L.C., H.O. Sanders, and A.M. Julin. 1979.
waterways near treated fields or buildings.1,2Toxicity of the herbicide glyphosate and several
Diazinon, also commonly found in urbanof its formulations to fish and aquatic
streams,18 is acutely toxic to many species ofinvertebrates. Arch. Environ. Contam. Toxicol.
fish, including salmon.3 Herbicides can also be toxic8:269-278.
to fish. According to the EPA, studies show that8. Morgan, J.D. et al. 1991. Acute avoidance
trifluralin, an active ingredient in the weed-killerreactions and behavioral responses of juvenile
Snapshot, "is highly to very highly toxic to bothrainbow trout ( Oncorhynchus mykiss) to Garlon
cold and warmwater fish."4 It was also shown in4, Garlon 3A, and Vision herbicides. Environ
a series of different tests to cause vertebralToxicol. Chem. 10:73-79.
deformities in fish.5 Oryzalin, the active ingredient9. Liong, P.C., W.P. Hamzah, and V. Murugan. 1988.
of Surflan, also is 'highly toxic' to fish.6 TheToxicity of some pesticides towards freshwater
weed-killers Ronstar and Roundup are also acutelyfishes. Malaysian Agric. J. 54(3):147-156.
toxic to fish.7,8 The toxicity of Roundup is likely10. McBride, J.R., H.M. Dye, and E.M. Donaldson.
due to the high toxicity of one of the inert1981. Stress response of juvenile sockeye salmon
ingredients of the product. In addition to direct( Oncorhynnchus nerka) to the butoxyethanol
acute toxicity, some herbicides may produceester of 2,4-dichlorophenoxyacetic acid. Bull.
sublethal effects on fish that lessen their chancesEnviron. Contam. Toxicol. 27:877-884.
for survival and threaten the population as a11. Little, E.E. 1990. Behavioral indicators of
whole. Glyphosate or glyphosate-containingsublethal toxicity of rainbow trout. Arch. Environ.
products can cause sublethal effects such asContam. Toxicol. 19:380-385.
erratic swimming and labored breathing which12. Zaffaroni, N.P. et al. 1986. The toxicity of 2,4-
increase the fish's chance of being eaten.9,10dichlorphenoxyacetic acid to the adult crested
2,4-D herbicides caused physiological stressnewt. Environ. Res. 41:79-87.
responses in sockeye salmon,11 and reduced the12. Suwalsky, M. et al. 1999. Toxic action of the
food gathering abilities of rainbow trout.12herbicide 2,4-D on the neuroepithelial synapse and
Other Aquatic Animals and Plants In addition toon the nonstimulated skin of the frog
fish, other marine or freshwater animals areCaudiverbera caudiverbera. Bull. Environ. Contam.
endangered by pesticide contamination. 2,4- D orToxicol. 62:570-577.
2,4-D containing products have been shown to be14. Caldwell, R.S. et al. 1979. Toxicity of the
harmful to newts,13 frogs,14 crabs,15 shellfish,16herbicides 2,4-D, DEF, propanil and trifluralin to the
and other aquatic species.17,18 The weed-killerDungess crab Cancer magister. Arch. Environ.
trifluralin is moderately to highly toxic to aquaticContam. Toxicol. 8:383-396.
invertebrates, and highly toxic to estuarine and15. Cheney, M.A., R. Fiorillo, and R.S. Criddle. 1997.
marine organisms like shrimp and mussels. DiuronHerbicide and estrogen effects on the metabolic
is also highly toxic to aquatic invertebrates.19activity of Elliptio complanata measured by
Since herbicides are designed to kill plants, itcalorespirometry. Comp. Biochem. Physiol.
makes sense that herbicide contamination of118C:159-164.
water could have devastating effects on aquatic16. U.S. EPA. Office of Pesticide and Toxic
plants. In one study, oxadiazon was found toSubstances. Office of Pesticide Programs.1989.
severely reduce algae growth.20 Algae is a staplePesticide factsheet: 2,4-dichlorophenoxyacetic acid.
organism in the food chain of aquatic ecosystems.Washington D.C., Sept.
Studies looking at the impacts of the herbicides17. Sanders, H.O. 1969. Toxicity of pesticides to
atrazine and alachlor on algae and diatoms inthe crustacean Gammarus lacustris. Technical
streams showed that even at fairly low levels,Papers of the Bureau of Sport Fisheries and
the chemicals damaged cells, blockedWildlife No. 25. US Dept. of Interior Fish and Wildlife
photosynthesis, and stunted growth in varyingService, Washington D.C. (Jan.)
ways.20 Another important class of organisms is18. Extoxnet. 1996. Pesticide Information Profile:
the cyanobacteria. Cyanobacteria live in aquaticdiuron. June.
environments as well as soil, and play a crucial role19. Ambrosi, D., A. Isensee, and J. Macchia. 1978.
in nitrogen fixation, helping plants convertDistribution of oxadiazon and phoslone in an
atmospheric nitrogen into nitrate compounds thataquatic model ecosystem. American Chemical
the plant can use. Trifluralin was found to inhibitSociety 26(1):50-53.
the growth of two common cyanobacteria at all20. U.S. Water News Online. 2000. Ecologist says
levels of application.21effect of herbicides on aquatic environment needs
Insects and Spiders In addition to killing insectresearch. July. tecosay7.html.
"pests," insecticides obviously have the potential21. Kobbia, I. A., et al. 1991. Growth criteria of two
to harm non-target insects such as beneficialcommon cyanobacteria isolated from Egyptian
natural predators and pollinators. Less obviously,flooded soil, as influenced by some pesticides.
weed-killers can also be harmful to beneficialWater, Air, and Soil Pollution 60:107-116.
insects. One study found that exposure to freshly22. Hassan, S.A. et al. 1988. Results of the fourth
dried Roundup (glyphosate) killed over 50 percentjoint pesticidetesting programme carried out by
of three species of beneficial insects: a parasitoidthe IOBC/WPRS-Working Group "Pesticides and
wasp, a lacewing and a ladybug. Over 80 percentBeneficial Organisms." J. Appl. Ent. 105:321-329.
of a fourth species, a predatory beetle was23. Extoxnet. 1996. Pesticide Information Profile:
killed."22 Moderate doses of the herbicide 2,4-D2,4-D. June.
severely impaired honeybee brood production. 2324. Washington State Department of
The herbicide oxadiazon is also toxic to bees,Transportation. 1993. Draft roadside vegetation
which are pollinators.24 Herbicides may hurtmanagement environmental impact statement,
insects or spiders indirectly as well, such as whenappendix B, B2-10.
they destroy the foliage that these animals need25. Asteraki, E.J., C.B. Hanks, and R.O. Clements.
for food and shelter. For example, spider and1992. The impact of the chemical removal of the
carabid beetle populations declined when 2,4-Dhedge-based flora on the community structure of
applications destroyed their natural habitat.25 Birdscarabid beetles (Col. Carabidae) and spiders
The insecticide diazinon is notorious for causing(Araneae) of the field and hedge bottom. J. Appl.
bird kills. Over 50 incidents involving the deaths ofEnt. 113:398-406.
up to 1000 birds have been documented in every26. US EPA. 1988. Diazinon; Ciba-Geigy
region of the U.S.95 Diazinon is so lethal to birdsCorporation, et al., petitioners. Federal Register
that the EPA estimates that between 15 and 8053(65):11119-11131. (April 5). 27. US EPA. 1998.
minutes of grazing on diazinon treated turf isR.E.D. facts rodenticide cluster. Office of
enough to kill a bird.26 Non-target birds may alsoPrevention, Pesticides, and Toxic Substances
be killed if they ingest poisoned grains set out as(July).
bait for pigeons and rodents.27, 28 Avitrol, a28. Extoxnet. 1996. Pesticide Information Profile:
commonly used pigeon bait, poses a large4- Aminopyridine. June. pips/4-aminop.htm.
potential for ingestion by non target grain feeding29. Duffard, R., L. Traini, and A. Evangelista de
birds. It can be lethal to small seed-eating birds.29Duffard. 1981. Embryotoxic and teratogenic
rodifacoum, a common rodenticide, is highly toxiceffects of phenoxy herbicides. Acta Physiol.
to birds. It also poses a secondary poisoningLatinoam. 31:39-42. 30. Lutz, H. and Y.
hazard to birds that may feed on poisonedLutz-Ostertag. 1972. The action of different
rodents.30 Herbicides can also be toxic to birds.pesticides on the development of bird embryos.
lthough trifluralin was considered "practicallyAdv. Exp. Med. Biol. 27:127-150.
nontoxic to birds" in studies of acute toxicity,31. MacKinnon, D.S. and B. Freedman.1993. Effects
birds exposed multiple times to the herbicideof silvicultural use of the herbicide glyphosate on
experienced diminished reproductive success inbreeding birds of regenerating clearcuts in Nova
the form of cracked eggs. Exposure of eggs toScotia, Canada. J. Appl. Ecol. 30(3):395-406.
2,4-D reduced successful hatching of chicken32. Marx, J et al. 1999. The relationship between
eggs,33 and caused feminization or sterility insoil and water, how soil amendments and
pheasant chicks.31 Herbicides can also adverselycompost can aid in salmon recovery. Soils for
effect birds by destroying their habitat.Salmon 1-18. 33. Savonen, C. 1997. Soil
Glyphosate treatment in clear cuts causedmicroorganisms object of new OSU service. Good
dramatic decreases in the populations of birds thatFruit Grower. 1995/6other.html.
had lived there.3234. Pell, M., B. Stenberg, and L. Torstensson. 1998.
Beneficial Soil Microorganisms One spoonful ofPotential denitrification and nitrification tests for
healthy soil has millions of tiny organisms includingevaluation of pesticide effects in soil. Ambio
fungi, bacteria, and a host of others. These27:24-28.
microorganisms play a key role in helping plants35. Santos, A. and M. Flores. 1995. Effects of
utilize soil nutrients needed to grow and thrive.glyphosate on nitrogen fixation of free-living
Microorganisms also help soil store water andheterotrophic bacteria. Lett. Appl. Microbiol.
nutrients, regulate water flow, and filter20:349-352.
pollutants.34 The heavy treatment of soil with36. Moorman, T.B. et al. 1992. Production of
pesticides can cause populations of beneficial soilhydrobenzoic acids by Bradyrhizobium japonicum
microorganisms to decline. According to soilstrains after treatment with glyphosate. J. Agric.
scientist Dr. Elaine Ingham, "If we lose bothFood Chem. 40:289-293.
bacteria and fungi, then the soil degrades. Overuse37. Fabra, A., R. Duffard, and A. Evangelista de
of chemical fertilizers and pesticides have effectsDuffard. 1997. Toxicity of
on the soil organisms that are similar to human2,4-dichlorophenoxyacetic acid in pure culture. Bull.
overuse of antibiotics. Indiscriminate use ofEnviron. Contam. Toxicol. 59:645-652.
chemicals might work for a few years, but after38. Arias, R.N. and A. Fabra de Peretti. 1993.
awhile, there aren't enough beneficial soilEffects of 2,4- dichlorophenoxyacetic acid on
organisms to hold onto the nutrients."35 ForRhizobium sp. growth and characterization of its
example, plants depend on a variety of soiltransport. Toxicol. Lett. 68:267-273.
microorganisms to transform atmospheric39. Singh, J.B. and S. Singh. 1989. Effect of
nitrogen into nitrates that plants can use. Common2,4-dichlorophenoxyacetic acid and maleic
landscape herbicides disrupt this process: triclopyrhydrazide on growth of bluegreen algae
inhibits soil bacteria that transform ammonia into(cyanobacteria) Anabaena doliolum and Anacystis
nitrite36; glyphosate reduces the growth andnidulans. Sci. Cult. 55:459-460.
activity of both free-living nitrogen-fixing bacteria40. Tözüm-Çalgan, S.R.D. and S.
in soil37 and those that live in nodules on plantSivaci-Güner. 1993. Effects of 2,4-D and
roots38; and 2,4-D reduces nitrogen fixation bymethylparathion on growth and nitrogen fixation in
the bacteria that live on the roots of beancyanobacterium, Gloeocapsa. Intern. J. Environ.
plants,39,40 reduces the growth and activity ofStud. 23:307-311.
nitrogen-fixing blue-green algae, 41,42 and inhibits41. Martens, D.A. and J.M. Bremner. 1993. Influence
the transformation by soil bacteria of ammoniaof herbicides on transformations of urea nitrogen
into nitrates.43,44 Mycorrhizal fungi grow with thein soil. J. Environ. Sci. Health B 28:377-395.
roots of many plants and aid in nutrient uptake.42. Frankenberger, W.T., Jr. and M.A. Tabatabai.
These fungi can also be damaged by herbicides in1991. Factors affecting L-asparaginase activity in
the soil. One study found that oryzalin andsoils. Biol. Fert. Soils 11:1- 5.
trifluralin both inhibited the growth of certain43. Bakalivanov, D. and O. Kostov. 1981. Soil
species of mycorrhizal fungi.45 Roundup has beenmicrobiological assessment of toxicity of
shown to be toxic to mycorrhizal fungi inalkanoate, amide and other herbicides. Acta
laboratory studies, and some damaging effectsMicrobiol. Acad. Sci. Hung. 28:141-146.
were seen at concentrations lower than those44. Beyrle, H.F. et al. 1995. Colonization of Orchis
found in soil following typical applications. 46,47morio protocorms by a mycorrhizal fungus:
Triclopyr was also found to be toxic to severaleffects of nitrogen nutrition and glyphosate in
species of mycorrhizal fungi,48 and oxadiazonmodifying the responses. Can. J. Bot. 73:1128-1140.
reduced the number of mycorrhizal fungal44. Jofré, E. et al. 1996.
spores.492,4-Dichlorophenoxyacetic acid affects the
Conclusion Pesticides have contaminated almostattachment of Azospirillum brasilense Cd to maize
every part of our environment. Pesticide residuesroots. Toxicol. 107:9-15.
are found in soil and air, and in surface and ground45. Kelley, W.D. and D.B. South. 1978. In vitro
water across the nation, and urban pesticide useseffects of selected herbicides on growth and
contribute to the problem. Pesticide contaminationmycorrhizal fungi. Weed Science Society of
poses significant risks to the environment andAmerica Meeting . Auburn University, Auburn,
non-target organisms ranging from beneficial soilAlabama. Pg. 38.
microorganisms, to insects, plants, fish, and birds.46. Estok, D., B. Freedman, and D. Boyle. 1989.
Contrary to common misconceptions, evenEffects of the herbicides 2,4-D, glyphosate,
herbicides can cause harm to the environment. Inhexazinone, and triclopyr on the growth of three
fact, weed killers can be especially problematicspecies of ectomycorrhizal fungi. Bull.Environ.
because they are used in relatively large volumes.Contam. Toxicol. 42:835-839.
The best way to reduce pesticide contamination47. Chakravarty, P. and S.S. Sidhu. 1987. Effects
(and the harm it causes) in our environment is forof glyphosate, hexazinone and triclopyr on in vitro
all of us to do our part to use safer, non-chemicalgrowth of five species of ectomycorrhizal fungi.
pest control (including weed control) methods.European Journal of Forest Pathology 17:204-210.
References:48. Moorman, T.B. 1989. A review of pesticide
1. Cooperative Extension Service Pesticideeffects on microorganisms and microbial
Information Project.1993. Extoxnet: Chlorpyrifos.processes related to soil fertility. Journal Prod.
Corvallis, Oregon: Oregon State UniversityAgric. 2(1): 14-23.
(September).